90W gear oils, which are found in the automotive oil category, are an important type of oil used in the transmission and differential systems of vehicles. These oils ensure the smooth operation of gear mechanisms working under high temperatures and pressure. The 90W feature indicates the viscosity and fluidity of the oil, which helps reduce wear in gear systems. Gear oils are generally recommended for vehicles operating under heavy loads and provide long-lasting use with regular maintenance. If you need to change the transmission or differential oil of your vehicle, you can check out reliable brands of 90W gear oils.